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• The impact of installation environment for a condensing unit in a plant room of apartment dwelling was evaluated. • As the louver window open area ratio decreases, the input power of the air conditioner increases in a logarithmic function. • As the rear clearance distance decreases, the input power of the air conditioner increases in a logarithmic function. • Insect screen in a plant room can deteriorate the performance of the condensing unit. • Using air-guide can offset the negative impact of louver window or insect screen on air discharge performance. In many countries, split-type air conditioners have been widely used in residential buildings due to the high energy efficiency. It has been reported that optimal heat exchange conditions are necessary for the condensing unit of the air source air conditioner to perform at its rated level, particularly when installed in an apartment building's plant room. This study analyzes the impact of installation parameters of a condensing unit of a split-type air conditioner, such as the clearance distance from the rear surface of the condensing unit, the louver angle, and the use of insect screen or air-guide, on the cooling performance. The findings from the experiments and the correlations between parameters and input power presented in this paper would be useful in designing residential buildings with split-type air conditioners and air conditioner plant rooms for optimal cooling performance. [ABSTRACT FROM AUTHOR]

Access to electricity remains elusive for over 700 million people worldwide. Although much attention has been given to solving this vexing problem in the context of communities in Sub-Saharan Africa and South Asia, often overlooked is that in even within so-called developed countries access to electricity might not be universal. It is estimated that more than 200,000 people living in North America do not have a connection to the electric grid. Many of these people live on Native American reservations or other Tribal Lands. Recently, there has been a concerted effort in the public, private, and non-profit sectors to electrify these homes with off-grid solar systems. This paper analyzes the electrical energy usage characteristics of 127 homes on the Navajo reservation in the southwestern United States. The homes have identical 3.8 kW solar arrays, 35.1 kWh 48 V gel lead acid battery banks, and 8 kW inverters. High-resolution inverter data was collected from these systems for a two-year period. Several statistical analyses were conducted on the data, including computing the statistical moments, creating empirical distributions of daily consumption, and analyzing consumption variation across different timescales. The results show average consumption of 2.78 kWh per day, but with a wide range of variation among homes. The implications of the analyses on pre-implementation system design, post-implementation interventions, and comparisons to incipient electricity consumption characteristics elsewhere in the world are discussed. The use of the average daily consumption in data-driven load estimation is evaluated and found to offer promising improvements over survey-based methods. • Analysis of 2-years of load data from off-grid residential solar systems on the Navajo Nation. • The study finds average daily consumption to be 2.78 kWh/day but with wide variation among the homes. • Statistical characteristics including statistical moments and quantiles are provided. • Analyses show how different component sizes could meet load and reliability targets. [ABSTRACT FROM AUTHOR]

• Optimal Window-to-Wall Ratios were recommended for various building orientation. • Integrated models with different glazing area and orientation combinations were proposed. • Daylight factor, air temperature and air velocity were computed for each test scenario. • Three optimal intervals of Window-to-Wall Ratio were determined respectively. • Intersection interval of the three subsets is the optimal interval of Window-to-Wall Ratio. Since the ratio of glazing and opaque areas on building facade has significant impact on the indoor visual and thermal comforts as well as energy consumption, the optimal Window-to-Wall Ratio is necessary to be explored for the rural residences with a large quantity in China. Due to the traditional dwellings has been representative of housing samples among rural residences, Sizhai traditional dwellings situated in Zhejiang Province were chosen as the study buildings in this paper. The building model is rotated to 20° increments clockwise to create 18 building orientation intervals. Furthermore, the Window-to-Wall Ratio of front facade for the building model was divided into 8 intervals at increments of 0.1, from [0.1–0.2] to [0.8–0.9]. Through indoor environment simulation, the daylight factor, air temperature and air velocity were computed for the test scenarios with different building orientation and Window-to-Wall Ratio combinations. Three optimal intervals of Window-to-Wall Ratios at a series of building orientations corresponding to the daylight factor, mean maximum indoor temperature and mean indoor air velocity are determined respectively, based on the criteria of national codes and thermal comfort ranges. The intersection interval of the three subsets is the optimal interval of Window-to-Wall Ratio for the study building. In addition, for verifying the accuracy of research results, two validation techniques (i.e., comparison of experimental measurement data, and comparison of computational results from other simulation tools) were adopted in this paper. [ABSTRACT FROM AUTHOR]

The application of a photovoltaic (PV) system for zero energy buildings is crucial to balance energy consumption. This paper investigated the potential of PV systems for buildings in different climate zones of China. The tilt angle, orientation, plot ratio, PV conversion efficiency and location were selected to study their influences on electricity production. The performance of the PV system was analyzed based on a residential building, and employed RETScreen in combination with TRNSYS. The results indicate that southwest China is the best place to develop zero energy buildings. Low-rise residential buildings can realize zero energy in China when the PV conversion efficiency is higher than 20%. However, an energy balance only occurs in the southwest when the PV conversion efficiency is 10%. For different building heights, with a high conversion efficiency (20%), the energy consumptions rates are less than 15 kW h/m2a all over China. In the southeast, the effect of the building shape on energy generation can be ignored due to the high solar elevation angle in the summer. Although the optimal tilt angle varies for different cities, the energy deviations are less than 10% when tilt angle is within 10° of the optimal angle. This study proposed a formula to evaluate the potential of a building PV system. The maximum difference between the simulated and calculated results is approximately 10%, which is reasonable and acceptable. This paper provides some references for the application of PV systems in zero energy buildings. [ABSTRACT FROM AUTHOR]

Highlights • A pre and post renovation energy use analysis of almost 90,000 renovated dwellings. • The (p)rebound effects explain only partly disappointing energy renovation results. • Effectiveness of renovations are dependent on state of building prior to renovation. • Effectiveness of renovations are dependent on type of occupant. • Deep renovations often save less energy than expected but are the most effective. Abstract Energy renovations often result in lower energy savings than expected. Therefore, in this study we investigate nearly 90,000 renovated dwellings in the Netherlands with pre and post renovation data of actual and calculated energy consumption. One of the main additions of this paper, compared to previous studies on thermal renovation, is that it only takes dwellings into account with the same occupants before and after renovation, using a large longitudinal dataset. Overall this paper shows new insights towards the influence of the energy efficiency state of a building prior to energy renovation, the type of building, the number of occupants, the income level of the occupants and the occupancy time on the actual energy savings, the energy saving gap and on the probability of lower energy savings than expected. We also investigate if the influence is different per type of thermal renovation measure. Some of the findings are: it is impossible to conclude which single thermal renovation measure is the most effective because this is dependent on the energy efficiency of the building prior to the energy renovation, type of building, income level and occupancy; occupants with a high income save more energy than occupants with low income; dwellings with employed occupants benefit more from improved building installations than dwellings occupied by unemployed occupants; The prebound and rebound effects are only part of the explanations for lower than expected energy savings; Deep renovations result more often in lower than expected energy savings than single renovation measures but nevertheless they result in the highest average energy saving compared to other thermal renovation measures. The results could be used for more realistic expectations of the energy reduction achieved by thermal renovations, which is important for (amongst others) policy makers, clients and contractors who make use of energy performance contracting, home owners, landlords and (social) housing associations and as a starting point to improve the energy calculation method. [ABSTRACT FROM AUTHOR]

This paper analyzes electricity use in buildings and explores key research questions related to assessing, rating, labeling, and benchmarking building energy use. The analysis reviews annual Energy Use Intensity (EUI) data from 3060 fully electric-powered buildings across six categories: residential, educational, offices, hospitals, hotels and restaurants, and wholesale and retail trade services. One-fifth of the analyzed buildings is derived from an energy dataset that offers a higher time-scale resolution, providing more detailed insights into energy usage patterns. The analysis employs various factors, including the seasonal variation factor (SVF), daily variation factor (DVF), monthly factor (M f), and hourly factor (H f), to gain a detailed understanding of actual energy usage at different time scales. The findings indicate that electricity use is less sensitive to seasonal variations than other energy carriers that provide heating and cooling. The paper provides hourly and monthly peak load percentages (PPL), which can indirectly assist in assessing hourly schedules for building energy performance simulations. The monthly energy use pattern varies between building categories, with high-energy months alternating between winter and summer. For non-residential buildings, high-energy hours correspond directly to the daytime, while for residential buildings, there is a shift towards the evening, and the daily amplitude is lower. Furthermore, the analysis of daily and monthly variability of heating energy carriers, even if non-electric, sheds light on the implications of electrification for these loads. • The study evaluates annual electricity data from 3060 fully electric-powered buildings. • Median EUIs are meaningful energy performance benchmarks by building category. • Residential and educational buildings exhibit EUIs of 90-120 kW h/m2. • Offices and hospitals demonstrate EUIs of 160-170 kW h/m2. • Monthly and hourly factors establish energy benchmarks for finer time resolution. [ABSTRACT FROM AUTHOR]

• Overheating regulations and calculation methods in 26 European countries were compared. • Most of the existing calculation methods are outdated and do not fit climate-proof buildings. • France requires a mixed-mode operation of naturally ventilated households. • The UK developed a heatwave-based calculation approach. • Comfort-based, multi-zonal, and time-integrated calculation approaches are needed. With the ongoing significance of overheating calculations in the residential building sector, building codes such as the European Energy Performance of Building Directive (EPBD) are essential for harmonizing the indicators and performance thresholds. This paper investigates Europe's overheating calculation methods, indicators, and thresholds and evaluates their ability to address climate change and heat events. e study aims to identify the suitability of existing overheating calculation methods and propose recommendations for the EPBD. The study results provide a cross-sectional overview of twenty-six European countries. The most influential overheating calculation criteria are listed the best approaches are ranked. The paper provides a thorough comparative assessment and recommendations to align current calculations with climate-sensitive metrics. The results suggest a framework and key performance indicators that are comfort-based, multi-zonal, and time-integrated to calculate overheating and modify the EU's next building energy efficiency regulations. The results can help policymakers and building professionals to develop the next overheating calculation framework and approach for the future development of climate-proof and resilient residential buildings. [ABSTRACT FROM AUTHOR]

The objective of this paper is to optimize the passive design of newly-built residential buildings in hot summer and cold winter region of China for improving indoor thermal comfort while reducing building energy demand. In this respect, this paper investigates the performance of a representative apartment building in the city of Shanghai and evaluates the optimum solutions by using a developed optimization approach, which includes three major steps of 1) setting the model for multi-objective optimization, 2) sensitivity analysis for reducing the dimension of input variables, and 3) multi-objective optimization by using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) coupled with the Artificial Neural Network (ANN), among which a novel indicator for evaluating the annual indoor thermal comfort of residential buildings of Shanghai named Comfort Time Ratio (CTR) is defined based on the modification of Szokolay’s theory in terms of bioclimatic analysis, and the impacts of passive design variables on the indoor thermal comfort and building energy demand in terms of different directions are comprehensively investigated. Results of the multi-objective optimization indicate that the residential buildings of Shanghai have a great potential in comfort-improvement and energy-saving. A series of novel optimal passive design tactics for residential buildings in Shanghai are derived accordingly which could be easily understood and conveniently carried out by the architects in practice. [ABSTRACT FROM AUTHOR]

Construction of residential buildings using off-site methods, in particular modular construction, is receiving considerable attention. However, the sustainability performance of modular buildings has rarely been investigated through a life cycle perspective. In this paper, a life cycle sustainability performance assessment framework is developed for modular buildings and its application is examined. In the first part of the paper, suitable life cycle sustainability performance criteria (SPCs) for modular buildings were developed and ranked. In this regard, potential SPCs were identified through a comprehensive literature review and expert interviews. These SPCs were then evaluated by construction experts through two questionnaire surveys against three evaluation criteria: applicability, data availability, and data accuracy. The evaluation criteria's weights were determined through a group decision making process using the Analytic Hierarchy Process (AHP) multi-criteria decision analysis (MCDA) method. Consequently, the experts' feedback was analyzed with the help of the Elimination and Choice Translating Reality (ELECTRE) outranking MCDA method and all the SPCs were ranked within their associated sustainability categories (i.e., environmental, economic, and social). In the second part of the paper, application of the proposed framework has been discussed and validated through a case study of a modular building in British Columbia, Canada. Sustainability performance of modular buildings in the proposed framework were assessed by developing aggregated sustainability indices for the selected SPCs and comparing them with corresponding benchmarks. In this regard, appropriate sustainability performance indicators (SPIs) under each selected SPC have been developed and calculated. Consequently, through an aggregation process, sustainability indices are developed using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) MCDA method. In this paper, the environmental life cycle performance of the case study building has been benchmarked and recommendations have been made for performance improvements. This research is deemed useful for the construction practitioners since it provides a methodical framework for life cycle sustainability performance assessment of modular buildings and assists with the selection of sustainable methods of construction. [ABSTRACT FROM AUTHOR]

Effectively utilizing low-grade thermal energy is a promising approach to mitigating greenhouse gas emissions while reducing the burden on centralized power grids. Current thermoacoustic heat pumps and power generators face challenges such as high onset temperature differentials and low performance. This paper addresses these challenges by introducing a gas-liquid resonator into a thermoacoustic combined heat and power systems to recover low-grade thermal energy in residential buildings. Through Sage modeling and calculations, the internal characteristics of the proposed system and its output performance under different operating conditions are explored. At a heating temperature of 350 °C, the system can generate 6.4 kW of output thermal power, 0.9 kW of electricity, and overall exergy efficiency is 79.3 %. Combining neural network models with case studies conducted in Spain and Finland, the system can annually save 5.6 MWh and 20.7 MWh in fuel energy, reduce emissions of 1374 kg and 5180 kg of carbon dioxide, and save a total cost of €611 and €2324, respectively. Furthermore, comparisons with other emerging micro-CHP systems highlight the efficiency of the proposed system. These results indicate the high potential of thermoacoustic combined heat and power systems in recovering low-grade thermal energy and achieving energy savings and emission reductions. • Introducing an innovative thermoacoustic micro-CHP system. • Achieving an exergy efficiency of 79.3 % under standard operating conditions. • One system can annually reduce household CO 2 emissions by 5180 kg. • Ideal for households, balancing lower output levels for both heat and electricity. [ABSTRACT FROM AUTHOR]

Retrofitting the building stock is pivotal to achieving climate neutrality by 2050. Most of the existing research on energy efficiency focuses on new residential buildings. The focus must shift to multi-building retrofits, thereby more frequently including non-residential buildings. As multi-building and non-residential projects are given a lighthouse role in achieving current global climate goals, more research should focus on this potential. This study covers single- and multi-building retrofitting projects. It also explores the role of non-residential projects, typical project settings, energy reduction achievements and the added complexity of the multi-building scale. The chosen methodology combines a systematic literature search with a subsequent critical metadata and full-text review of more than 80 peer-reviewed scientific papers. The results show that the number of studies in the research field has increased substantially in the last few years, while the research mostly originates from Europe and focuses on the residential building typology. This research is partly transferable to similar climate zones elsewhere, while a large proportion of climate zones remains unexplored. The current body of definitions and requirements regarding energy retrofitting is an impediment to the comparability of projects, and particularly the multi-building scale is in need of international guidance. Future research should focus on making retrofit measures more applicable internationally, while unifying project boundaries. The stronger inclusion of non-residential retrofitting projects as lighthouse projects including social aspects is needed. Retrofitting that covers energy production and sharing has great potential and should be seen as an opportunity. [Display omitted] • Multi-building retrofitting is emerging but requires clearer international guides. • Europe stands for most publications, motivated by policies and climate goals. • Most of the reported energy retrofits do not satisfy "deep retrofitting" goals. • Multi-building retrofitting results in added social and technical difficulties. • Clearer international guidelines and best practices needed to reach climate goals. [ABSTRACT FROM AUTHOR]

The 2023 revision of the Energy Performance of Building Directive underlines the need to consider the whole life cycle emissions for buildings. The decarbonization targets could not be achieved if reduction of energy demand in the operational phase is accompanied by a high energy resource use in the whole life. This paper proposes a novel investigation of an energy renovation project, involving both building envelope components and space heating system. The adopted method is based on the life cycle assessment, in the variant cradle-to-gate with options, to analyze and compare the design data achieved through an analysis of product (embodied) and use (operational) stages. Different solutions for energy improvement of the building performance are identified, and the scenario with the lowest embodied energy was found to be more energy efficient globally. The most effective scenario, with energy and CO 2 savings of 39% and 40% is characterized by a weight of embodied energy and emissions of 6.5% and 6.9%, respectively. Given the rise of the weight of the embodied energy in the whole life cycle of future buildings, the life cycle assessment will become crucial for sustainable design and in the transition to an energy-efficiency built environment. [Display omitted] • The impact of life cycle analysis in the process of energy efficiency is investigated. • The "cradle-to-gate" with options approach is implemented. • The efficiency of walls and windows involves the greater use of energy resources. • The most energy-efficient scenarios from an operational and non-operational point of view are different. • The scenario identified in the analysis of A1-A4 phases allows a higher total energy saving. [ABSTRACT FROM AUTHOR]

In the past, the network environment usually adopted a distributed design, which often caused a series of problems such as cumbersome performance adjustment and high energy consumption. The software-defined network adopts a new design method that is different from the traditional network environment, which is hierarchical management and centralized control. This design method can achieve overall planning and can adjust the network structure in a comprehensive and flexible manner. In order to solve the disadvantages of distributed design, this paper innovatively proposes the use of sleep heuristic algorithm to realize dynamic adjustment of WAN energy consumption and performance in SDN network environment, and defines a new network evaluation method. This mechanism flexibly adjusts the network structure through users' attention and feedback on network performance, which can not only ensure network performance, but also effectively reduce network energy consumption. At the same time, the mechanism was verified using a simulation environment. Experimental results show that the mechanism is universal and can be easily implemented in various scenarios. The close integration of low-carbon design concepts with high-rise residential buildings can fully improve the energy-saving effect of buildings, reduce energy consumption, and help build a green and environmentally friendly residential city. Based on this, this article combines theoretical practice, first analyzes the definition of low-carbon design concepts, and then discusses the reasons why high-rise residential buildings need low-carbon design concepts, and proposes specific applications of low-carbon design concepts in high-rise residential building design. There will be some reference and help for the design of similar projects in the future. [ABSTRACT FROM AUTHOR]

• Investigated strategies that can deliver NZE performance for high-rise residential buildings in Australia. • It was challenging for tropical, subtropical and cold temperate climates to meet the NZE targets. • Design and optimisation of the envelope was effective in overcoming the challenges imposed by the more demanding climates. • The impacts of shading from neighbouring buildings presented the largest obstacle to energy production through the façade. • Study demonstrated a need to include density factors in the design consideration for NZE high-rise residential designs. Net-Zero Energy (NZE) buildings are gaining popularity globally as a solution to reduce operational energy usage and limit greenhouse gas emissions in the building industry. Their deployment is occurring rapidly as many countries are planning to make it mandatory for new developments. Despite the advancements in research in the various aspects of NZE, significant barriers do exist to its successful adoption and implementation, particularly with respect to high-rise residential buildings which are becoming a major portion of the housing supply in Australia. One of the challenges attributed to the achievement of NZEB performance is the uncertainty involved in selecting appropriate solution strategies that could deliver quality performances. This paper investigated strategies that can deliver NZE performance for high-rise residential buildings in Australia. A calibrated model of 26 storey high-rise apartment building with 396 units was prepared for detailed analysis of NZE strategies using building simulation. The impact of various interventions was evaluated across cities in five climate zones in Australia and a guideline for solution sets that can deliver the goal for each climate zone is presented. The findings show that NZE performance for high-rise residential buildings can be realised in Australia, albeit with some limitations. While the tropical, subtropical and cold temperate climates appear to be more challenging, proper design and optimisation of the envelope proved to be effective in overcoming the challenges imposed by the more demanding climates. The impacts of shading from neighbouring buildings and objects presented the largest impediment to energy production through the façade. [ABSTRACT FROM AUTHOR]

The paper evaluates the potential energy efficiency benefits for dynamic sliding exterior shades suitable for windows of both new and existing buildings. In particular, the analysis outlined in the paper summarizes the energy performance of dynamic sliding shades when applied to windows for apartment units located in various US climates. A series of sensitivity analyses is performed using a detailed whole-building simulation coupled with modeling techniques of dynamic envelope systems to determine the optimal positions for the dynamic sliding shades to minimize the annual demand for US housing units. Several operation strategies are evaluated using continuous and stepped settings of the positions for the dynamic sliding shades using monthly, daily, and hourly adjustment frequencies. The results of the analyses indicate that the dynamic shades have significant energy efficiency potential for all US climates and design conditions with annual savings in HVAC energy end-use of over 50% especially in hot and mild climates. The performance of the dynamic shades is even higher for large and single-pane windows indicating that these systems can serve as retrofit alternatives to window replacements. • New and low-cost dynamic and insulated shading systems are introduced. • Energy benefits of the dynamic shades are assessed for residential buildings. • Optimal controls for the dynamic shades are determined for US climates. • Dynamic shades achieve over 50% reduction in heating and cooling energy use. [ABSTRACT FROM AUTHOR]

This paper presents a multi-objective method of analysing the energy efficiency associated with upper class houses in Gated Communities in Arid Zones. The application of building energy regulations has an impact on improving energy efficiency. Energy codes identify the effective techniques that could help in achieving energy efficiency on the building scale, but there is a gap in applying these techniques on the existing urban community scale. This paper proposes a method of integrating energy retrofitting techniques with renewable energy systems to achieve energy efficiency in residential gated communities. The study applies simulation analysis to determine the energy performance when applying these strategies using different building materials in light of the requirements stipulated in the Egyptian Energy Code for Residential Buildings (EECRB). The results show that the entire gated community's energy usage is reduced by 88.68 percent and suggest a framework for achieving energy efficiency in existing buildings and communities. [ABSTRACT FROM AUTHOR]

This paper establishes the need to act at a city scale to reduce energy use and improve sustainability in general. The paper evaluates the plans that the City of Fargo (Climate zone 6), North Dakota has established to grow in a sustainable manner. As part of this effort, the City of Fargo is participating in the Georgetown University Energy Prize Competition to reduce the energy use of residential and municipal buildings. As such, the City is engaged in assessing, defining, designing and implementing the Go 2030 plan (2012) as the basis for a sustainable future. This paper reviews and evaluates several methods of city-scale assessments and identifies distinguishing characteristics of these tools and assessments and creates a categorization to make the methods ordered and understandable. The two broad categories developed are (1) category- and (2) indicator-based models of urban sustainability. Further, this paper reviews the tools through a literature search and compares the City of Fargo's Go 2030 plan against these categorizations. Based on this evaluation this paper proposes a framework that has the potential to fill the gaps in the current Go2030 plan. [ABSTRACT FROM AUTHOR]

Following the 21st Conference of the Parties (COP 21), the 2015 Paris Agreement on Climae Change strengthens the attempts of the European Union to decarbonize the building sector and to facilitate the transition from fossil fuels towards cleaner energy. The last version of the Energy Performance of Buildings Directive 2018/844/EU is human centric and requires the integration of indoor environmental quality assessment, simultaneously with energy performance and cost-optimal requirements. In other words, efforts to improve the energy efficiency of buildings must actively contribute on reducing the building stock's climate impact while ensuring healthy indoor climate conditions, wellbeing and productivity. This paper introduces the cost-optimal analysis and indoor environmental quality assessment for nearly zero-energy buildings in temperate climate. The study presents several nearly zero-energy buildings (NZEB) scenarios for residential buildings, which include measures that are either upgrades that can be implemented in the as-built case study building or different other configurations of thermal envelope, technical systems and on-site renewable energy production. The cost-optimal analysis results show that among the investigated scenarios, the lowest global cost is achieved by the as-built house, which is an all electric building that has passive house envelope, mechanical ventilation with heat recovery, heat pump and solar collector. Furthermore, the study reveals that with the implementation of PV panels, the primary energy demand can be reduced with 55% at a global cost increase of only 3%. The results and data can be used to compare energy efficincy measures and the related costs between EU Member States. • Cost-optimal levels of energy performance and indoor environment are investigated for a nearly zero-energy building (NZEB). • Passive house design combined with PV panels, results in net-zero energy or greater energy production than consumption. • Three of the proposed NZEB scenarios have a higher energy production than consumption. • NZEB can be achieved with a lower insulation, if it is combined with efficient technical system and/or renewable energy production. • Indoor environmental quality was assessed following a full year of measured data in the occupied building. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique preconditions, specific characteristics for use can be boundary conditions. • Energy use, users' behavior, lighting are correlated conditions within buildings. • Boundary conditions can help explain the occupants' behaviour and the use of spaces. • Knowledge of boundary conditions helps to understand how to design buildings. • Boundary conditions can be building/ user/ input-values and method-specific. This paper aims to review the boundary conditions (B/C) in specific categories (energy, building use, and lighting) within non-residential buildings to pave the way to a better understanding of users' requirements and needs of the built environment. For this paper, B/C are understood as unique preconditions, specific characteristics for use, determining specific features of buildings, enabling an accurate understanding of non-residential spaces concerning energy use, user behaviour, and lighting. This paper describes the results of an overall quantitative (1st method) review and a systematic review (2nd method) of boundary conditions and their factors within different types of non-residential buildings from the users' perception. Followed by a qualitative experts' literature review (3rd method) on B/C within offices, schools, and hospitals chosen by a team of international experts working together on Subtask A: User perspective and requirements, Task 61 IEA (International Energy Agency): Solutions for daylighting and electric lighting. The first review method led to the selection of 21 papers. The second method resulted in the selection of 7 papers out of 93,143 found in Scopus; during the 3rd review, experts collectively chose 74 additional papers focussing on the users' factors contributing to specific B/C. The scope of this paper is limited only to offices, schools, and hospitals. Based on the findings, the authors recognise a broad definition of boundary conditions from specific values, and conditions to interconnected factors, user profiles, functions of the building types, and operating hours. This paper is an overview of B/C factors found in the literature that can help explain the occupants' behaviour and the use of spaces. B/C are often type of building/user/location/situation/simulation input-values and method-specific. Therefore, they cannot be widely applicable but offer patterns and help to understand the correlations between various factors shaping the built environment. A better comprehension of the reasons for identifying B/C and their factors can help in developing a deeper knowledge of how we use buildings to find optimal ways to design them. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to design energy consumption modeling systems to predict the energy consumption value due to today's energy use in cities increasing. A new Modified Fish Migration Optimization Algorithm-based Numerical Moment Matching (MFMOA-NMM) technique is applied as an initial indeterminacy evaluation method to forecast the electrical power use in large-scale datasets of single-family residential homes with the application of main characteristics. To develop energy modeling, the DesignBuilder is used. The energy performance of the homes is assessed by combining these techniques. With the application of the information from the energy audit and data of the assessor (8368 single-family homes), four effective parameters including attic insulation R-value, the efficiency of air conditioners (SEER), type of the window, and the area of homes are inputted into the model improvement. Waterloo in Iowa is selected as the case study. The results showed that the yearly electrical power use expected is equal to 10,195 kWh which is within 5% of the experimental electrical power use. Also, the monthly expected electrical power use Average Bias Error is equal to 2.4% and the Coefficient of Variation with the Root Average Square Error is equal to 6.7%. This technique can be applied to create a small group of typical buildings to show the energy performance of a bigger group of buildings. • Energy consumption modeling to predict energy consumption for single-family homes in Waterloo. • Energy performance optimization by a Modified Fish Migration Optimization Algorithm. • Combining the introduced new algorithm with Numerical Moment Matching technique. [ABSTRACT FROM AUTHOR]

Hemp-based building envelopes have gained significant popularity in developed countries, and now the trend of constructing houses with hemp-clay blocks is spreading to developing countries like Morocco. Investigating the hygrothermal behavior of such structures under actual climate conditions is essential for advancing and promoting this sustainable practice. This paper presents an in-depth experimental characterization of a commercial hemp-clay brick that has been exposed to the outdoor environment for four years, in addition to field measurements on a building scale demonstration prototype. Additionally, the study simulates 17 representative cities to assess the hygrothermal performance and energy-saving potential in each of Morocco's six existing climate zones, using the EnergyPlus engine. The experimental campaign's findings demonstrate excellent indoor air temperature and relative humidity regulation within the hemp-clay wall building, leading to satisfactory levels of thermal comfort within hemp-clay wall buildings. This is attributed to the material's good thermal conductivity and excellent moisture buffering capacity (found to be 0.31 W/mK and 2.25 g/m2%RH), respectively). The energy simulation findings also point to significant energy savings, with cooling and heating energy reductions ranging from 27.7% to 47.5% and 33.7% to 79.8%, respectively, as compared to traditional Moroccan buildings. [Display omitted] • Experimental characterization of thermal conductivity, sorption isotherm, and moisture buffering capacity of hemp bricks. • Assessment of indoor thermal comfort and energy demand in a hemp-based building across 17 cities in Morocco. • Hemp-clay bricks demonstrated excellent humidity regulation with a moisture buffer capacity of 2.25 g/m2%RH. • Hemp-clay walls can achieve energy savings ranging from 27.7%–47.5% for cooling and 33.7%–79.8% for heating in Morocco. [ABSTRACT FROM AUTHOR]

The low-density residential building clusters exist widely in Chinese towns and rural areas, and have advantages to achieve zero emission with lower energy density and larger available space. However, the path for these areas to achieve zero emission is not clear yet and needs to be investigated. This study attempts to explore the approaches that the low-density residential communities achieve carbon neutrality considering local and external energy resources comprehensively. Regional zero-emission energy systems are designed and optimized to meet users' multiple energy demands. Five scenarios are established and compared based on the different combinations of energy resources. Results show that the regional self-sufficiency ratio can be 72.9%, and external energy supply is required even for the low-density areas. The PV installation area can be up to 100%, and the utilization of the local municipal waste can significantly increase the self-sufficiency ratio, about 24% of the power generation. The systems' economic performance is not attractive yet, with the minimum payback period about 8 years. If the carbon tax is adopted and the external fuels' price decreases, applications of the systems could be feasible. This paper would provide guidelines and suggestions to promote the zero-emission energy systems in the low-density areas. [ABSTRACT FROM AUTHOR]

Improving the level of energy efficiency required by building codes for refurbishments and new construction is a powerful lever for reducing greenhouse gas emissions. This paper explores how technological, social, political, and economic factors interact and shape the evolution of the energy efficiency in building codes. Existing approaches to the evolution of standards focus primarily on adopting individual or multiple technologies or products, but only peripherally explore the feedback dynamics between innovation, diffusion, and standardization (IDS.) To fill this void, I draw on the revelatory case of Switzerland, because the Swiss standards have continuously improved since 1970, whereas in many other countries improvements have stagnated after the recovery from peaks in energy prices. The paper's contribution is, first, a qualitative, structural model which endogenously formalizes the IDS-dynamics of standard improvement. I find that the co-evolution of voluntary and legal building codes have enabled a continuous improvement of the standards even in the absence of economic pressures. And second, I use the model for policy analysis, which indicates that several obvious policies might cause policy resistance and could result in uneconomical, counter-intuitive outcomes. Policy interventions have to dynamically balance the speed of innovation and the ability of system agents to change. [ABSTRACT FROM AUTHOR]

At present, building energy consumption is growing rapidly in China and it accounts for about 30% of the total energy consumption. Solar energy, as a type of renewable energy, will greatly alleviate the pressure of the building energy consumption if it is widely used in residential buildings. Firstly, this paper briefly introduced the characteristics and distribution of solar energy resources in China. Secondly, this paper summarized the three types of solar energy utilization: light-gathering utilization, solar energy photo-thermal utilization and photovoltaic utilization. Among them, photo-thermal technology is suitable for solar-powered residential buildings (SPRBs) in terms of current technology and economy. Thirdly, authors analyzed the passive SPRBs and active SPRBs, where the active SPRBs are more intelligent due to its flexibility and controllability. Based on the above analysis, to realize the harmony between solar technologies and building appearance, authors put forward building integrated solar energy (BISE) design in the consideration of technology and aesthetics. The development and application of solar technologies in residential buildings embodies the concepts of energy conservation, environmental protection and sustainable development, and it will promote the development of building energy efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Environmental pressure from residential energy use is projected to significantly increase by 2030. Different environmental policy measures provide different incentives for “environmentally responsive” consumer choices and behavioural responses. There is a great energy saving potential in residential buildings of Lithuania. Compared to the other EU countries with similar climate conditions, energy consumption for residential heating is approximately 1.8 times higher in Lithuania. About 60% of Lithuanian population resides in multi-apartment buildings constructed during 1961–1990. The aim of the paper is to define the main drivers of residential energy use in Lithuania and to compare energy saving technologies in terms of energy saving potential and costs in Lithuanian residential buildings. Seeking to achieve the aim the main tasks of the paper are to analyse theoretical issues of the main drivers of residential energy use; to analyse residential energy use trends in Lithuania and to compare these trends with other EU member states; to define the main drivers of residential energy use by applying correlation analysis; to analyse policies aiming to reduce energy consumption in residential buildings and their impacts on GHG emission reduction. The comparative study of residential energy use in Lithuania and several old EU member states showed that residential energy use per capita in Lithuania is significantly lower than in old EU member states because of the lower income per capita and lower living standards. The economic and technological factors are the main driving forces of final energy consumption in all compared EU member states; however the impact of different factors varies between countries. The comparative analysis of energy saving and GHG emission reduction potential and costs in residential buildings provided by different studies showed that the most cost-effective instruments were appliance standards, energy efficiency obligations, Demand Side Management programs, public benefit charges and labelling. [Copyright &y& Elsevier]

The COVID-19 pandemic has significantly affected people's behavioral patterns and schedules because of stay-at-home orders and a reduction of social interactions. Therefore, the shape of electrical loads associated with residential buildings has also changed. In this paper, we quantify the changes and perform a detailed analysis on how the load shapes have changed, and we make potential recommendations for utilities to handle peak load and demand response. Our analysis incorporates data from before and after the onset of the COVID-19 pandemic, from an Alabama Power Smart Neighborhood with energy-efficient/smart devices, using around 40 advanced metering infrastructure data points. This paper highlights the energy usage pattern changes between weekdays and weekends pre– and post–COVID-19 pandemic times. The weekend usage patterns look similar pre– and post–COVID-19 pandemic, but weekday patterns show significant changes. We also compare energy use of the Smart Neighborhood with a traditional neighborhood to better understand how energy-efficient/smart devices can provide energy savings, especially because of increased work-from-home situations. HVAC and water heating remain the largest consumers of electricity in residential homes, and our findings indicate an even further increase in energy use by these systems. [ABSTRACT FROM AUTHOR]

Abstract: The paper deals with the development of a tool used for the life cycle assessment of residential buildings located in three different European towns: Brussels (Belgium), Coimbra (Portugal) and Luleå (Sweden). The basic tool focuses on the structure and the materials of the buildings and permits the evaluation of the Embodied energy, Embodied carbon and yearly energy consumption. For that purpose, a different set of original data is taken into account for each location, in which the monthly temperatures, energy mix, heating and cooling systems are defined. The energy consumption, being for heating space or water, for cooling or for lighting is transformed into CO2 emissions to deduce the Operational carbon as well. The influence of the energy mix can therefore be assessed in the basic tool. As a matter of fact, the heating and cooling systems habitually used in the three countries are also of great importance. The District Heating system, is, for instance, incorporated in the basic tool. The presence of solar water heater or photovoltaic panels is also strongly influencing the operational carbon. After a short literature review on building LCA and the description of the basic tool, the software Pleiades + Comfie combined with Equer is used to achieve the complete LCA for one building using two different load bearing frames. The results of the calculations for Brussels climate are verified against these software results. The dependence of the results to parameters such as climate, energy mix and habits is then discussed in the companion paper. [Copyright &y& Elsevier]

The energy retrofitting of residential stock is not always straightforward where heritage protected housing is concerned. In southern Europe, many examples built under the Modern Movement codes are now obsolete in terms of energy efficiency. The aim of this paper is to assess the potential for improvement of comfort conditions and energy efficiency in Mediterranean heritage residential buildings, through the incorporation of passive strategies in keeping with preserving heritage values. Long-term monitoring and field tests in representative flats of the case-study building were carried out and, focusing on a single example, adaptive comfort equations were used to assess results. The passive strategies considered are the thermal isolation of the air cavities of walls, changing window frames, optimizing window glazing, and setting up regular mechanical ventilation rates for indoor air changes. Although simulation results generally predict a better energy performance after testing retrofit strategies, the potential decrease in energy demand is more noticeable than the potential improvement in comfort conditions. • The improvement of comfort and energy efficiency in a heritage building is assessed. • Long-term monitoring and field tests were carried out in representative flats. • Passive strategies in keeping with preserving heritage values were examined. • Adaptive comfort equations were used to assess results focusing on one flat. • Energy efficiency improvements are more noticeable than those of comfort conditions. [ABSTRACT FROM AUTHOR]

Future building energy management systems will have to be capable of adapting to variation in the rate of production of energy from renewable sources. Controllers employing a model predictive control (MPC) framework can optimise and schedule energy usage based on the availability of renewably generated energy. In this paper, an MPC using artificial neural networks (ANNs) was implemented in a residential building. The ANN-MPC was successfully tested and demonstrated good performance predicting the building's energy consumption. The controller was then modified to function as an economic MPC (EMPC) to optimise demand flexibility (i.e., the ability to adapt energy demands to fluctuations in supply). The operational costs of energy usage were associated with this demand flexibility, which was represented by three flexibility indicators: flexibility factor, supply cover factor, and load cover factor. The results from a day-long test showed that these flexibility indicators were maximised (flexibility factor ranged from −0.88 to 0.67, supply cover factor from 0.04 to 0.13, and load cover factor from 0.07 to 0.16) when the EMPC controller's demand flexibility was compared to that of a conventional proportional-integral (PI) controller. The EMPC framework for demand flexibility can be used to regulate on-site energy generation, grid consumption, and grid feed-in and can thus serve as a basis for overall optimisation of the operation of heating systems to achieve greater demand flexibility. • An ANN-MPC was developed and tested in a residential building. • ANN models and an MPC framework were validated against measurements in buildings. • An EMPC to maximise the demand flexibility of residential buildings was developed and tested. [ABSTRACT FROM AUTHOR]

Highlights • The U-value impact on the thermal performance of residential buildings was analyzed. • 192000 buildings were randomly generated and evaluated using dynamic simulation. • Six geometry-based indexes were correlated with the buildings performance. • Higher U-values can decrease energy consumption in lower latitudes. • Higher and wider U-value intervals increase the geometric freedom for lower latitudes. Abstract Contrarily to what happens in northern European countries, buildings in the Mediterranean region are prone to overheating. Consequently, it is important to better understand the role that the thermal transmittance of the building envelope elements has on air-conditioning consumptions. This paper analyzes the effect of different U -values on building design in the Mediterranean area. 192 000 residential buildings were randomly generated for sixteen distinct locations and the energy consumption was assessed for each. It was found that in northern Mediterranean locations, as U -values decreased, energy consumption also decreased. However, in warmer climates, low thermal transmittances tended to significantly increase energy consumption. Hence, the lower the latitude, the higher the U -values should be, in order to prevent increasing the cooling demands. Additionally, geometry-based indexes were correlated with the building's energy performance. For high U -values, it was found that bigger buildings worsen the energy performance and larger windows tended to improve it. For low U -values, bigger north-facing windows were beneficial. There is an adequate interval of values for which the geometry has a lower impact, which is wider and higher for lower latitudes, thus meaning that not only does the building performance improve but architects are also freer to explore alternative designs. [ABSTRACT FROM AUTHOR]

Abstract The goal of this paper is to evaluate the advantages achieved through the adoption of low impact energy saving strategies for an independent natural gas fired boiler heating system in a recently built residential building in Rome. For this purpose, an existing apartment was selected as a case study and dynamically simulated in TRNSYS with which the model was validated. Low impact retrofit solutions and heating system management were considered as possible solutions to achieve energy savings. The chosen retrofit solutions consist of envelope elements replacements and building automation controls improvement while heating system management depends on occupants' behavior. Overall, 36 scenarios were considered, starting from the combination of 3 comfort temperature set-points, 2 insulation levels for transparent components, 2 types of zone comfort set-point control with 3 dead-band temperatures. Each case is evaluated in terms of energy results and economic results. The simulation results provide energy savings up to 44% when windows are replaced lowering their transmittance nearby 32%. The choice of a proportional control for zone temperature set-point compared to a simple on-off control guarantee energy saving up to 39% when temperature set-point is low (19 °C) and controls dead-band is 0.5 °C. The effect of different temperature control dead-bands is higher when proportional controls are adopted (up to 40% passing from 2 to 0.5 °C dead-band for 19 °C set-point). Energy consumption reductions up to 63% are achieved if the indoor temperature set-point is lowered 2 °C, underlining the importance of occupants' behavior. At last, an analysis on socio-economic impacts was performed, based on the results of a previous study focused on the externality costs due to pollutants emissions. Highlights • Energy advantages achieved through the adoption of low impact energy saving strategies for an independent gas fired boiler were evaluated. • An existing apartment of a modern residential building in Rome was selected and dynamically simulated in TRNSYS. • 36 energy saving scenarios were considered. • Each case was evaluated in terms of energy and economic results. • An analysis on socio-economic impacts was performed, based on the externality costs due to pollutants emissions. [ABSTRACT FROM AUTHOR]

Highlights • Calculation of life cycle costs and payback periods of building intervention packages. • Calculation of financial gap between nZEB and cost optimality. • Study covers single and multi-family house buildings for 2 periods and climate zones. • Ranking of intervention packages based on cost effectiveness and energy efficiency. Abstract Nearly zero energy buildings (NZEBs) constitute one of the main pillars of the energy policy of European Union (EU). Greece has recently established a clear definition for NZEB, however the interdependence between cost-optimality and the energy performance of NZEB has not been adequately studied. The present work includes a cost effectiveness analysis among different energy efficiency interventions for the existing residential Greek building stock. To this end, the calculation of the investment as well as the operating and maintenance cost for a wide range of energy efficiency measures were carried out. All calculations were based on the methodology defined in the Directive 2010/31/EU on the energy performance of buildings, while the economic evaluation assumptions were based on the EN 15459-1 standard. The goal is the determination of the most cost effective (cost-optimal) measures that are applicable for two different building types; Single Family House (SFH) buildings and Multi-family House (MFH) apartment blocks, taking into account the period of their construction and the climate zone they belong to. Furthermore, the scope of the paper includes also the assessment of the gap between these measures and the NZEB thresholds. The analysis showed that in various cases and depending on the exact national NZEB definition, NZEBs are located beyond cost optimality. [ABSTRACT FROM AUTHOR]

Abstract: The success of modeling the sustainable performance of the residential building envelope will be to a great extent associated to the sustainable energy performance indicators used. The sustainable energy performance indicators that these building assessment models are developed around should be chosen by taking into account the targeted objectives. However, it is very common to find building performance assessment models that do not take into account these considerations and therefore have a limited capability and scope. This leads to inadequate aggregate indicators for the actual assessment of the sustainable performance of the building envelope for a sustainable energy efficient building. The focus of this paper is to investigate the principal sustainable energy performance indicators for modeling the sustainable performance of the residential building envelope and develop an approach for determining the most appropriate sustainable energy performance indicators. In doing that, this paper provides an overview of previous research on sustainable energy performance indicators and discusses conceptual framework for developing sustainable energy performance indicators. In order to identify these indicators that influence the capability of building performance assessment models, a comprehensive survey of construction industry professionals was conducted using questionnaire survey technique while the data was analyzed using correlation analysis techniques. [Copyright &y& Elsevier]

Abstract: Combined heat and power (CHP) is a well-known technique for producing heat and power simultaneously onsite. However, the micro level of this technology has just been recently introduced around the world, and expected to widely spread. Therefore, identifying the optimal size of such systems would give them the potential for being more beneficial. In this paper, a generic deterministic linear programming model, which aims to minimize expected annual cost of the system, has been developed. This model is capable of optimally determining the optimal size (electrical rating) of a micro CHP (μCHP) unit and the optimal size (thermal rating) of a back-up heater for any given residential demand regardless of the type of μCHP technology. An investigation has been conducted to identify economically the optimal μCHP investment for three typical residential dwellings in England. The four candidate μCHP technologies that have been considered in this paper are: internal combustion engine (ICE), Stirling engine (SE), solid oxide fuel cell (SOFC), and proton exchange membrane fuel cell (PEMFC). Sensitivity analyses have been conducted to understand the influence of some important key parameters on decision making regarding the deployment of residential μCHP systems. [Copyright &y& Elsevier]

Abstract: In early 2006 the European Commission launched the GreenBuilding Programme (GBP), aimed at improving the energy efficiency of existing as well as newly constructed non-residential buildings in Europe on a voluntary basis. Building owners from different sectors are participating in the programme, e.g., public authorities with schools, hospitals or swimming pools, companies from the services and industry sectors with office buildings, sports centres and hotels. The aim of the paper is to provide a summary analysis of the results of the GBP over its almost four-year operation – from the launch of the programme in 2006 until the end of 2009. By the end of 2009, 167 Partners had joined the programme with almost 300 buildings from all sorts of fields and sectors of operation. The total savings achieved by the Partners are 304GWh/year. The buildings themselves may vary in age, size and use, but they all have in common the energy performance, which goes far beyond the average performance of buildings in the participating countries. The paper focuses on efficiency measures implemented in the participating buildings and the achieved energy savings. [Copyright &y& Elsevier]

Abstract Understanding the development of the trends in the ownership of different appliances in a historic context in various countries of the world can not only provide important insights for understanding the dynamics of adoption of different appliances, but can also help with foresight: how the future may develop for these or other, new appliances on the market. Although available literature in household appliances energy consumption, energy management and energy efficiency has seen some advances, there is a clear lack in the literature on household appliance ownership. In this paper, historic data is gathered and analysed for several groups of appliance types (white appliances, brown appliances and small appliances) for 12 countries representing four continents, when available since 1970 to date. Countries representing different parts of the world were selected to present an overview on household appliances ownership and energy consumption. One of the first conclusions of the study is that there is little or no information in many countries from South America, Africa or South Asia. Refrigerators, freezers and washing machines ownership are an example of most other white goods. Brown goods appeared in the market at very different time, depending on each one (from the 70s to the late 90s) and their ownership growth is much higher than for the previous ones. Most of small line appliances ownership has not reached saturation yet. Highlights • Development of the trends in the ownership of appliances in a historic context. • There is a clear lack in the literature on household appliance ownership. • Historic data is gathered and analysed for white, brown, and small appliances. • 12 countries representing four continents, when available since 1970 to date. • Most of small line appliances ownership has not reached saturation yet. [ABSTRACT FROM AUTHOR]

Abstract: A companion paper presented the life cycle inventory (LCI) calculation model for buildings as a whole, developed within a global methodology to optimise low energy buildings simultaneously for energy, environmental impact and costs without neglecting the boundary conditions for thermal comfort and indoor air quality. This paper presents the results of a contribution analysis of the life cycle inventory of four typical Belgian residential buildings. The analysis shows the relative small importance of the embodied energy of a building compared to the energy consumption during the usage phase. This conclusion is even more valid when comparing the embodied energy of energy saving measures with the energy savings they realise. In most studied cases, the extra embodied energy for energy saving measures is gained back by the savings in less than 2 years. Only extremely low energy buildings might have a total embodied energy higher than the energy use of the utilisation phase. However, the sum of both remains small and the energy savings realised with these dwellings are large, compared to the energy consumption of average dwellings. [Copyright &y& Elsevier]

• Data about DHW in residential buildings were collected by survey in Southern Italy. • Contextual and personal factors influencing DHW usage were considered. • Descriptive statistics were performed to characterize DHW by climatic zone. • Inferential statistics were conducted to discover DHW usage patterns. • Four clusters of dwellings were identified considering DHW daily usage hours. In European efficient buildings, the share of energy use for DHW is a significant percentage of the heat requirement. The evaluation of DHW energy demand and consumption patterns has been neglected in the past and studies are located in Northern countries. This paper presents a survey conducted in Southern Italy. Descriptive statistics were performed to characterize DHW production by climatic zone. Inferential statistics were conducted to discover significant contextual and personal variables and identify usage groups. The most used energy source was biomass (49.3%), followed by methane gas (37.7%). Fireplaces were installed in the coldest zone, in detached houses, more in small municipalities (36%), and low-income families (32%). Solar systems were in 8% of dwellings having income higher than 28000€. Four clusters of dwellings were identified considering the daily usage hours. The eldest and less numerous households fell into the cluster with the lowest usage (3.5 h). Households with a percentage <25% of unemployed components had more probability to belong to clusters with more DHW usages. The paper contributes to fill the investigation in the Mediterranean area and provides a systematic approach to expand the limited knowledge about the influencing factors on the DHW production and usage. [ABSTRACT FROM AUTHOR]

The paper provides a systematic evaluation of the optimal optical characteristics of smart windows to maximize their energy efficiency benefits when deployed for residential buildings. The evaluation accounts for a wide range of design specifications and operation conditions of housing units including building orientation, window sizes, and climatic zones. Using integrated analysis aimed to minimize energy use required to heat and cool housing units, the optimal design and control settings are determined for two types of smart windows including those that can switch between only clear and dark tint states and those that can transition to multiple intermediate tint levels. The results from a series of sensitivity analyses show that the required design optical specifications for the smart windows could depend on several variables including primarily climate characteristics and window features including size, orientation, and U-value. Significant energy savings can be achieved by smart windows relative to the code-compliant static fenestration systems ranging from 21% in cold climates to 5% in warm climates. These energy savings can be achieved using stepped controls to set the tint levels of the smart windows. Additional albeit slight savings can be obtained through gradual controls for those smart glazing that have the capabilities to transition to intermediate tint levels. • A new analysis approach is presented for selecting optical properties of smart glazing. • Optimal optical properties for smart glazing can be identified for any residential building. • Energy efficiency benefits of smart glazing are enhanced using optimal optical properties. • Over 20% energy use can be saved by smart glazing relative to code-compliant systems. [ABSTRACT FROM AUTHOR]

Building energy consumption forecasting is crucial for energy managers and policymakers. However, acutely predicting the energy consumption of any building is more important in energy efficiency benchmarking of buildings. Energy benchmarking is a precise technique for measuring, tracking, and reducing end-use energy usage of buildings by employing comparative scenarios. Bottom-Up energy consumption assessment has been used in several studies to evaluate a collection of buildings' energy performance to a standard. Traditionally, researchers have used a single approach to predict the energy use of buildings and to conduct benchmarking. However, it has been found that doing so frequently compromises the accuracy of the predicted energy use of buildings. It also has an adverse effect on the buildings' energy benchmarking framework results. This paper will provide an energy benchmarking framework for residential buildings based on the blending techniques of multiple approaches. Over 3000 datasets were gathered from the Indian city of Jaipur. In order to analyse the trends in energy consumption, the data were divided into categories based on economic levels. The data is then subjected to some fundamental statistical analysis, along with several approaches are blended to forecast the energy consumption of the buildings with the highest accuracy. These benchmark levels set guidelines for assessing and recognising strong performance while also identifying underperforming buildings and giving them more priority for energy efficiency improvement. The technique may be used for different metropolitan levels and climatic conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of two benchmark models for post-world war II residential buildings. • Average energy use intensity per household (archetypes A and B) were 166 and 155 kWh/m2/year. • Models validated with four-year monitoring data on energy consumption. • Households are dominated by senior adults and their occupancy profiles are presented. • Findings on energy needs and use intensity are useful in temperate and continental climates. In the context of the European carbon neutrality targets, building benchmarks are a key issue for the renovation of existing buildings. Although there are various benchmark methods for energy efficiency characterization, their application to the residential sector is still limited. This paper developed two building simulation models for post-world war II houses in Belgium based on data from post-occupancy measurements and field survey campaigns. The study reports the energy characteristics and occupancy profiled of detached single-family houses. An analysis of energy consumption (electricity and natural gas) and a walkthrough survey were conducted between 2016 and 2019. The benchmark model's validity has been further checked against public statistics and verified through model calibration and monthly energy bill comparison. Two reference models representing 633.702 post-WWII single-family houses in Belgium were created and validated. The first archetype has an average energy use intensity of 166 kWh/m2/year and represents detached single-family houses built between 1945 and 1969. The second archetype has an average energy use intensity of 155 kWh/m2/year and represents detached single-family houses built between 1970 and 1990. The paper provides a timely opportunity to evaluate the real performance of post-world war II most common archetypes concerning design assumptions and how building professionals can turn the energy performance gap challenge to their advantage. The findings on energy needs and intensity are useful for creating future renovation scenarios for similar archetypes in Western European countries. [ABSTRACT FROM AUTHOR]

Highlights • Solar plus—PV integration with batteries and load control—improves PV end-user economics. • Literature on solar plus is reviewed. • The value of solar plus depends on technology costs, customer rate structures, load profiles. • Load control devices are more cost-effective than batteries at current battery costs. Abstract Batteries and load control devices can increase the value of distributed solar photovoltaics (PV) from multiple perspectives—end-user, utility, and social. This review paper summarizes the end-user economics of battery and load control technologies that increase the value of PV by controlling and temporally shifting PV output, an approach referred to as “solar plus.” Solar plus can increase on-site PV use. The literature shows that these values justify the incremental costs of solar plus devices for a wide variety of technologies, geographies, and customer load profiles, especially for customers in three rate structure contexts: where PV is sold to the grid at a lower value than the customer’s retail rate, in time-of-use rates where peak periods do not coincide with PV output, and in demand charge rates where load peaks do not coincide with PV output. Rate structure and policy reform may be necessary to ensure that increasing solar plus deployment provides both end-user and system-level benefits. [ABSTRACT FROM AUTHOR]

Fuel cell based micro-combined heat and power (CHP) units used for domestic applications can provide significant cost and environmental benefits for end users and contribute to the UK’s 2050 emissions target by reducing primary energy consumption in dwellings. Lately there has been increased interest in the development of systematic methods for the design of such systems and their smoother integration with domestic building services. Several models in the literature, whether they use a simulation or an optimisation approach, ignore the dwelling side of the system and optimise the efficiency or delivered power of the unit. However the design of the building services is linked to the choice of heating plant and its characteristics. Adding the dwelling’s energy demand and temperature constraints in a model can produce more general results that can optimise the whole system, not only the micro-CHP unit. The fuel cell has various heat streams that can be harvested to satisfy heat demand in a dwelling and the design can vary depending on the proportion of heat needed from each heat stream to serve the energy demand. A mixed integer non-linear programming model (MINLP) that can handle multiple heat sources and demands is presented in this paper. The methodology utilises a process systems engineering approach. The model can provide a design that integrates the temperature and water flow constraints of a dwelling’s heating system with the heat streams within the fuel cell processes while optimising total CO 2 emissions. The model is demonstrated through different case studies that attempt to capture the variability of the housing stock. The predicted CO 2 emissions reduction compared to a conventionally designed building vary from 27% to 30% and the optimum capacity of the fuel cell ranges between 1.9 kW and 3.6 kW. This research represents a significant step towards an integrated fuel cell micro-CHP and dwelling design. [ABSTRACT FROM AUTHOR]

Sunken courtyard is known as one of the basic elements in vernacular architecture, especially in hot-arid zones. Even though the significant influence of sunken courtyards in energy saving is known for a long time, their suitability for occupants has not yet been precisely investigated. Therefore, this paper presents a detailed analysis of the suitability of vernacular sunken courtyards for modern-day building design. Three traditional dwellings with sunken courtyards, which currently are used as educational environments, are considered in the city of Yazd, Iran. The study is based on open and close-ended questionnaires so as to evaluate psychological and environmental factors that could affect the perception and satisfaction level of the occupants. The results of the close-ended questionnaire reveal that the three sunken courtyards could effectively reduce the traffic noise level. In addition, these spaces have positive impression on the occupants as they find them as comfortable, pleasant, calm and quiet areas. The results of the open-ended questionnaire show that the sunken courtyards are capable of providing a strong link to the green areas, incentives for learning, comfortable temperature level in summers, more concentration and creativity. On the other hand, the sunken courtyards fail in providing sufficient daylight and acceptable thermal comfort during winters. Recommendations will be provided to improve the performance of sunken courtyards in order to meet the requirements for occupants’ comfort. [ABSTRACT FROM AUTHOR]

Based on a household energy use survey, this paper explores the technical and economic potential of residential energy savings in a Chinese city, Xiamen. The survey adopted a similar questionnaire used by the U.S. EIA's Residential Energy Consumption Survey (RECS), covering the end-uses of cooking, water heating, plug-in appliances, lighting and space cooling. The analysis shows that the technical potential of energy savings in Xiamen's residential buildings is significant, around 20%. Of the technical potential, about two-thirds to four-fifths are cost-effective from a whole society perspective. The cost-effectiveness was evaluated by comparing the Levelised Cost of Conserved Energy (LCOCE) of advanced technical measures with the actual cost of conserved energy. The actual cost of energy is defined by adding the carbon emission cost and hidden government subsidies over the retail prices of energy. About three-quarters of the technical energy-saving potential in Xiamen come from adopting efficient household appliances, therefore, further tightening the energy efficiency standards for key household appliances and promoting wide diffusion of efficient models of appliances by various effective financial incentives are essential for achieving residential energy savings in China's “Hot Summer and Warm Winter” region where Xiamen locates. [ABSTRACT FROM AUTHOR]

Airtightness testing is widely undertaken to assess the as-built performance of dwellings, in support of achieving energy and ventilation strategies. Mandatory schemes operate in some countries, such as the UK, to ensure that dwellings are built in accordance with their design air permeability. However, testing is only useful if the results give a true picture of the airtightness of the building. Previous literature has investigated factors which could influence airtightness test results but has not questioned data quality, despite the pressure on builders to achieve design targets. This paper presents air permeability results from the largest UK dataset, comprising 144,024 dwellings tested under the Air Tightness Testing and Measurement Association (ATTMA) scheme. The data show an unexpected distribution of test results with narrow peaks just within test targets. Such results were not expected theoretically but do reflect findings in other fields where performance-based targets are in place. Such a close match between design and tested airtightness may be achieved by remedial works taking place during the test rather than afterwards. Recommendations are made with respect to quality assurance systems, design guidance and on-site sealing practices to increase the likelihood of long-term airtight buildings being constructed first time. [ABSTRACT FROM AUTHOR]

Germany's climate goals require over 75% of its housing stock to be retrofitted for energy efficiency. An important question for Germany and other countries is, what minimum energy efficiency standard should be mandated for housing retrofits so as to reduce CO2 emissions economically efficiently? It has long been known that the marginal costs of energy efficiency increase as standards are pushed higher, and therefore the marginal costs of CO2 abatement increase, but at the same time energy consumption reduces, thereby reducing CO2 emissions. This paper investigates where the social optimum lies between these two effects. In addition to a large database of house sale advertisements containing price and energy efficiency data, it uses two semi-official data sources of modelled and actual energy efficiency upgrades in Germany. It finds that retrofitting to a modestly high standard of about 70 kWh/m2/y entails marginal costs of CO2 abatement comparable to current CO2 prices. However, each step to a higher standard increases these by up to an order of magnitude, with absurdly high marginal costs of CO2 abatement for the highest standards. German policymakers are currently pushing for higher minimum standards, but money could better be spent retrofitting more houses to less stringent standards. • Policymakers seek to drive energy efficiency in buildings to ever higher levels. • But costs of CO2 abatement rise extremely sharply as standards tighten. • Use cost data on retrofits of German buildings to various efficiency standards. • Retrofits to current standards are at the limit of CO2 abatement efficiency. • Driving standards higher increases CO2 abatement cost by an order of magnitude. [ABSTRACT FROM AUTHOR]

• Provided a platform to test various residential building control systems. • Used probability of occupancy to determine setback temperature when unoccupied. • Integrated optimizer with adaptive and occupancy control. • Generated dynamic electricity tariff based on wholesale electricity pricing. • Evaluated the peak load shaving potential with dynamic pricing and optimization. Energy consumption in buildings continues to rise with increased deployment of energy-consuming equipment such as Heating, Ventilation, and Air Conditioning (HVAC) amid a growing world economy. Renewable energy is projected to comprise a majority of the future electricity supply, but the intermittent nature of renewables means that consumption must respond to dynamic supply for optimal utilization. This paper proposes a novel HVAC control strategy for residential buildings using the adaptive comfort model, considering occupancy through probability and real-time information, and optimizing the HVAC schedule to reduce cost, maintain thermal comfort, and respond to the dynamic availability of renewable energy while being generalizable to different situations. To validate this approach, the Universal CPS Environment for Federation (UCEF) co-simulation platform is used to connect advanced building controls with the building energy simulation software EnergyPlus. Simulations are performed for a residential building in Sacramento, CA during a typical summer week. Economic impacts, energy consumption, and thermal comfort are analyzed for traditional, adaptive, and occupancy-based control strategies under demand-based, tiered, and fixed electric tariff systems. Simulation results show that occupancy consideration, adaptive thermal comfort, and optimization can reduce cost by 50.1 %, electricity consumption by 52.9 %, and discomfort by 56.2 % compared to traditional fixed setpoints. The ability of the proposed HVAC control strategy to shift energy consumption away from peak times under a demand-based tariff system is qualitatively analyzed and findings suggest that maximum load-shifting on a grid-scale is attained using occupancy consideration with optimized control and demand-based pricing. For individual residential buildings, similar economic benefits can be gained using the less-complex adaptive HVAC control strategy with existing tiered or simple electric tariff systems. [ABSTRACT FROM AUTHOR]

This paper evaluates the ability of EN16573:2017 to isolate and quantify the energy efficiency and renewable generation contributions of multifunctional balanced ventilation systems. These systems integrate an air-source heat pump with heat recovery ventilation and two similar, yet physically different configurations (C1 and C2) are assessed. Heat pump operation does not influence heat recovery performance for widely used configuration C1 but does influence for novel configuration C2. This study shows that while EN16573:2017 can isolate the energy efficiency (heat recovery exchanger) and renewable generation (heat pump) contributions for configuration C1, it fails when applied to configuration C2. Measurements undertaken using EN16573:2017 on configuration C2 revealed an overall coefficient of performance of 5.07, split 51% heat exchanger with heat pump off (phase 1), and 49% heat pump (phase 2 minus phase 1). If this result were obtained for configuration C1 the respective contributions would be 51% energy efficiency and 49% renewable generation. While these contributions cannot be resolved using EN16573:2017 for configuration C2, it can be achieved using two additional measurement planes in the incoming airstream. These showed an 88%:12% contribution from the heat exchanger and heat pump, respectively. While accurate, this result under-estimates the true heat pump contribution, as its positive impact on the heat exchanger efficiency boosts its contribution from 51% (phase 1) to 88% (phase 2). This paper acknowledges that heat pump operation leverages a 37% increase in heat exchanger performance and proposes a that the respective contributions of the heat exchanger and heat pump should be 42%:58%. • Novel combined heat recovery ventilation system is experimentally investigated. • Additional measurement planes are required beyond the EN 16573-2017 standard. • Energy efficiency and renewable generation are individually assessed in a dynamic system. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a methodology to monitor the performance of buildings in a Zero Carbon City from the occupant perspective. Masdar City in Abu Dhabi is hailed as the World''s pioneering Zero Carbon Zero Waste city. The initial phase of construction is complete and the first students have moved into the residential quarters of the Masdar Institute of Science and Technology (MIST) in September 2010. Although the study monitors both Carbon and Waste, this paper outlines a Post Occupancy Evaluation (POE) to assess the resident''s satisfaction and building performance at MIST. The research focuses on the role that user behaviour and satisfaction plays on energy efficiency. It is hoped that such an approach will allow building performance to be normalized for user behaviour and to examine how best to commission, explain and handover complex low energy developments to new residents. It is hoped that the residents’ reaction and adaptation to the first Zero Carbon Zero Waste city will provide valuable insights that can be applied to future low energy developments. [Copyright &y& Elsevier]